The only hard thing about Seymour is that he turns you into a zombie so you have to waste a characters turn changeing him/her back to normal before he cast's full-life, but in saying that he wastes a turn casting Full-life as well (If you cured the character that is) apart from that and his special attack (Forgot what it's called) he's easy...ish
Anyway what about that Bitch of a Final Boss in that Gameboy Zelda